Couplings of various types for the joining of fluid conduit are widely utilized and marketed. One such coupling is the non-pressure balanced joint type adapted to effect a swivel movement and particularly suited for the joining of conduit containing fluid at relatively high pressures. Such swivel couplings are widely utilized in a variety of hydraulic applications and typically are comprised of relatively rotatable tubular housing sections interfitted to form a swivel joint. The joint provides for the relative rotation while being also designed to withstand the internal fluid thrust forces urging separation of the housing sections. Prior art devices of the foregoing type are disclosed in U.S. Pat. Nos. 2,343,491; 2,677,933; 2,749,151; and 3,142,498.
In an exemplary type construction, the swivel joint is generally comprised of a pair of interfitting tubular housings mechanically joined through a thrust load bearing which permits relative rotation between the housings. An annular elastomeric seal is normally interposed between the interfitted sections for preventing fluid leakage of contained high pressure fluid to outward of the joint.
Various factors characterize such couplings in that the elastomeric seal is subject to wear and the adverse effects of aging. As a consequence, the seal requires periodic replacement and therefore represents a regular maintenance item for which access to the seal area is necessary. Access normally involves a separation or disassembly of the separate housing components. However, the designs of such joints is frequently dominated by the thrust and bearing features as to result in a construction of undue complexity that is difficult to disassemble for servicing. Because of the complexity of construction, disassembly for replacement of the seal is inherently resisted by the features which provide for the bidirectional rotational action and thrust resistance between the interfitted sections during operation of the swivel. Since the thrust and rotational features represent operational parameters in contrast with the maintenance feature of seal replacement, the former are normally given dominant design consideration at the expense of the latter. By that standard, maximum bearing life is obtained under the loads to be encountered for effectively enhancing life expectancy of the joint as a whole.
Typically, the rolling bearing members are generally pins or balls and are utilized in one of three basic constructions by which the bearing races are incorporated. Each of the three basic constructions are commercially available and include a first construction as for example marketed commercially by Aeroquip Corp. as their model FS5900 Series Swivel Joint. In this construction a roller or ball thrust bearing is interposed between the joined housing sections. The bearing is generally contained in one of the housings by a rotational torque resisting threaded retainer. For incorporating the swivel feature, this bearing method is normally utilized with a significantly large first housing and a relatively complex rotational resistant bearing retention structure.
A second commercial form of such couplings is marketed by Hydraulic, Inc. as its S series In-Line 3000 psi/Full Flow joint. Complementary roller races in this construction are formed in the overlap between housings in which pins or balls are loaded through an outwardly extending aperture that communicates with the races. The fluid conducting swivel of this construction requires the bearing be disassembled in order to replace the resilient seal. Moreover, because of the critical location of the loading aperture, it requires that particular attention be given to the permanency of the aperture with the view of providing for ready access when seal replacement becomes necessary.
A third commercial embodiment is of a type for example marketed by T-M Manufacturing Company in which a tubular sleeve like component is interposed between the interfitted housing sections. The sleeve member affords complementary races with the inner of the housing sections thereat and in which the pins or balls are loaded via an aligned aperture extending radially outward through the sleeve. When the races are loaded, the aperture is permanently closed. Securement of the tubular member to the outer of the housing sections involves a relatively complex rotational resistant threaded connection resulting in considerable and otherwise unnecessary bulk. Tampering with the permanent closure of the roller loading aperture has proven to be a problem in that construction.
By virture of the dominant consideration given to the design of the thrust and rotational bearing features in the foregoing structures it should be apparent that the servicing aspects have been largely ignored in being regarded as a secondary consideration. As a consequence, servicing of such devices of the prior art have proven unnecessarily difficult and expensive. Despite recognition of the problem, a ready solution therefore had not heretofore been known.